doc: announce changes in IPsec xform struct

doc: announce changes in IPsec xform struct

IPsec xform struct would be updated to include IPsec SA lifetime
configuration. The existing member 'esn_soft_limit' would only track
ESN. And as sequence number control is getting introduced,
'esn_soft_limit' may not indicate the number of packets processed.
Replace that with a new structure to cover all lifetime cases with
support for specifying both soft and hard lifetimes.

ESN control introduced by https://patches.dpdk.org/patch/95808/

Signed-off-by: Anoob Joseph <anoobj@marvell.com>
Acked-by: Akhil Goyal <gakhil@marvell.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
Acked-by: Jerin Jacob <jerinj@marvell.com>